Biocompatibility of resin-modified filling materials.
Increasing numbers of resin-based dental restorations have been placed over the past decade. During this same period, the public interest in the local and especially systemic adverse effects caused by dental materials has increased significantly. It has been found that each resin-based material releases several components into the oral environment. In particular, the comonomer, triethyleneglycol di-methacrylate (TEGDMA), and the 'hydrophilic' monomer, 2-hydroxy-ethyl-methacrylate (HEMA), are leached out from various composite resins and 'adhesive' materials (e.g., resin-modified glass-ionomer cements [GICs] and dentin adhesives) in considerable amounts during the first 24 hours after polymerization. Numerous unbound resin components may leach into saliva during the initial phase after polymerization, and later, due to degradation or erosion of the resinous restoration. Those substances may be systemically distributed and could potentially cause adverse systemic effects in patients. In addition, absorption of organic substances from unpolymerized material, through unprotected skin, due to manual contact may pose a special risk for dental personnel. This is borne out by the increasing numbers of dental nurses, technicians, and dentists who present with allergic reactions to one or more resin components, like HEMA, glutaraldehyde, ethyleneglycol di-methacrylate (EGDMA), and dibenzoyl peroxide (DPO). However, it must be emphasized that, except for conventional composite resins, data reported on the release of substances from resin-based materials are scarce. There is very little reliable information with respect to the biological interactions between resin components and various tissues. Those interactions may be either protective, like absorption to dentin, or detrimental, e.g., inflammatory reactions of soft tissues. Microbial effects have also been observed which may contribute indirectly to caries and irritation of the pulp. Therefore, it is critical, both for our patients and for the profession, that the biological effects of resin-based filling materials be clarified in the near future. (+info)
Evidence for bacterial causation of adverse pulpal responses in resin-based dental restorations.
The widespread use of resin and resin-monomers for bonding of dental restorations to dentin has occurred because of a fundamental shift in the view that injury to the pulp is induced by restorative procedures. While, for many years, the toxic effects of restorative materials were thought to be of crucial importance in the development of adverse pulpal responses, the key role of bacterial leakage at the restoration-tooth interface is now well-recognized. Consequently, if optimal conditions for the preservation of pulpal health are to be ensured, dental restorations should provide an impervious seal against the surrounding tooth structure. However, polymerization shrinkage and contraction stresses induced during setting, as well as a variety of technical difficulties encountered during the clinical operation, often produce less than perfect results. Therefore, modern restorative procedures involving resin and resin-bonded restoratives must still rely on the ability of the pulp to cope with the injurious elements to which it may be exposed during and after the procedure. This review examines factors that may govern the pulp's response to restorative procedures that involve adhesive technologies. An assessment is made of the risks involved as far as the continued vital function of the pulp is concerned. It is concluded that an intact, although thin, wall of primary dentin often enables the pulp to overcome both toxic material effects and the influences of bacterial leakage. In contrast, the pulp may not do equally well following capping of open exposures with resin composites. A dearth of controlled clinical studies in this area of dentistry calls for confirmation that pulpal health prevails over the long term following the use of total-etch and resin-bonding techniques. (+info)
Diagnosis of secondary caries.
A systematic review of the diagnosis of dental caries was produced before the conference. It did not include the diagnosis of secondary or recurrent caries. This was a wise decision because what little literature exists on the subject potentially clouds the issue. Diagnosis is a mental resting place on the way to a treatment decision. A vital part of caries diagnosis is to decide whether a lesion is active and rapidly progressing or already arrested. This information is essential to plan logical management. However, lesion activity should be judged in the patient. Thus, research on the diagnosis of secondary caries must be carried out in vivo and this usually precludes histological validation. Even if such validation is possible, it has its own problems, particularly in distinguishing recurrent from residual caries. The diagnosis of secondary caries is very important since so many restorations are replaced because dentists think there is a new decay. It will be important to establish valid criteria for the diagnosis of active secondary caries, which will be facilitated by the suggestion that secondary caries is no different from primary caries except that it occurs next to a filling. This implies that it can be seen clinically and on a radiograph, next to a restoration. (+info)
A study of cavity preparation by Er:YAG laser. Effects on the marginal leakage of composite resin restoration.
The purpose of this study was to evaluate marginal leakage of composite resin restoration from cavities prepared by Er:YAG laser. The observation of the dentin surface after the application of laser irradiation was performed by LSM, the cutting surface showed a rough surface similar to scales, and exposed dentinal tubules were observed without striations or a smeared layer formation that were observed when using a rotary cutting device. Leakage tests revealed no significant differences in the marginal seal for both enamel and dentin between cavities prepared by Er:YAG laser irradiation and when using an air-turbine. In this study, the usefulness of cavity preparation by Er:YAG laser irradiation in composite resin restoration was suggested. (+info)
Analysis of pulpal reactions to restorative procedures, materials, pulp capping, and future therapies.
Every year, despite the effectiveness of preventive dentistry and dental health care, 290 million fillings are placed each year in the United States; two-thirds of these involve the replacement of failed restorations. Improvements in the success of restorative treatments may be possible if caries management strategies, selection of restorative materials, and their proper use to avoid post-operative complications were investigated from a biological perspective. Consequently, this review will examine pulp injury and healing reactions to different restorative variables. The application of tissue engineering approaches to restorative dentistry will require the transplantation, replacement, or regeneration of cells, and/or stimulation of mineralized tissue formation. This might solve major dental problems, by remineralizing caries lesions, vaccinating against caries and oral diseases, and restoring injured or replacing lost teeth. However, until these therapies can be introduced clinically, the avoidance of post-operative complications with conventional therapies requires attention to numerous aspects of treatment highlighted in this review. (+info)
Evaluation of adhesive defects using an ultrasonic pulse-reflection technique.
The purpose of this study was to examine the application of an ultrasonic pulse-reflection technique for the evaluation of adhesive defects. First, the sonic velocities in the enamel and dentin of human molars and bovine incisors were measured with a pulsar receiver attached to an ultrasonic transducer. The identification of the dentino-enamel junction and pulp-dentin interface using the ultrasonic method based on intrinsic sonic velocities showed good agreement with the actual measured thicknesses. Next, a cemented restoration with artificial faults was prepared. Half of the Au-Ag-Pd alloy plate area was cemented to the dentin slab using luting resin cement. The adhesive interface was evaluated with a high-resolution ultrasonic imaging system. Clear internal faults were evident from the ultrasonic tomogram. The findings of this study suggest that the ultrasonic pulse-reflection technique may be useful for inspecting and imaging structural defects of adhesive interfaces. (+info)
EPMA observation between dentin and resin interfaces. Part 1. Comparison of wet and dry technique after short-term stored in water.
The study was to evaluate the marginal leakage of wet or dry dentin condition after restoration on short-term. In the study we used Photobond adhesive system and Single Bond adhesive system. The specimens were prepared from premolars. A class V cavity was prepared at the CEJ with a high-speed hand piece and #010 round diamond point. The cavity's walls and floors were etched with phosphoric acids of the test materials by wet and dry bonding techniques. The specimens were cross-sectioned longitudinally through the center of the cavities with a low speed diamond micro-cutter and polished with carbide paper (#600-1200) after storage in distilled water for 1 day, and silver nitrate staining. Specimens were viewed with EPMA for elemental distribution of calcium, nitrogen and silver on the resin-dentin interface. The uptake of silver particles was less in samples treated with the wet-bonding technique when compared with dry-bonding technique. This in vitro study showed that bonding technique is important in establishing a seal along the restoration margins to control marginal leakage. (+info)
A new method for assessment of marginal sealability of dental restorations.
A new testing system was developed for assessment of marginal sealability of dental restorations. It was constructed with a thermocycle loading line and a leakage detecting line partitioned from each other by the restoration under evaluation. The hot and cold solutions of rhodamine B as a tracer were alternately circulated in the thermocycle loading line by the switching of six solenoid valves. Marginal leakage of the tracer into distilled water circulating in the detecting line was periodically monitored by a spectrometer while thermocycling the restoration. The leakage data could be analyzed on the basis of an empirical formula. In application of this method, the durability of a complete seal against thermal changes was estimated on three teeth each of which was restored with an inlay, an amalgam or a glass ionomer. (+info)